I have instructions for tightening hot and cold water seats in a Symmons Temptrol Tub/Shower valve. The instructions say to tighten the seats to 15 foot pounds. I've watched some plumbers doing this on youtube videos but have never seen a torque wrench used. Do you pros use a torque wrench? I've never used a torque wrench so I don't have any concept of what 15 foot pounds would be. Is it finger tight, hand tight or cranked down?